This invention relates to a method for enveloping and assembling plates into a group for use in an electrochemical cell and the group of enveloped and assembled plates produced thereby.
A number of different types of secondary batteries are constructed of adjacent positive and negative plates separated by a suitable porous separator material. Illustrative of such secondary batteries are lead acid batteries (including both flooded cell and recombinant types of lead acid batteries), metal hydride batteries, reusable alkaline batteries, etc.
Enveloping the separator material around either the positive or negative, or both, has become the preferred method of separation. Enveloping typically involves wrapping the separator around the plate and sealing the separator along both sides. Sealing methods employed include ultrasonic welding, heat sealing and pressure sealing, the latter being the most widely used for lead acid batteries.
For some applications, particularly with metal hydride cells, it is desirable to envelope both plates with the separator material. In such applications it may be critical that the positive and negative plates do not come into contact prior to enveloping, and that any dust generated during enveloping from plates of one polarity not come into contact with plates of the opposite polarity. This could be accomplished by separately enveloping two types of plates and subsequently assembling the plates into cells. However, this approach would require additional and time consuming handling.
It is an object of this invention to provide a method for enveloping positive and negative plates and assembling the plates into a cell that minimizes the time required for such operations. It is a further object to provide an assembly of enveloped plates having a unique structure.